- 30C

+ 40C

Housing

Thermal insulation

A well-insulated house or apartment is extremely important, both in terms of your own budget and the environment, which affects us all. Also, there are strict legal rules and checks con-cerning thermal insulation.An overall thermal insulation level of K55 applies to the dwelling as a whole.A heat transmission coefficient U of less than 0.6 W/m2K must be observed for the outer walls.

Winter Summer

Keeps cold out

Keeps heat out

Pleasantly warm inside

Pleasantly cool

inside

Thermal insulation

High insulation value

To satisfy the conditions imposed in

most European countries,

the U-values of the wall must be less

than 0.6 W/m2K.

The tables below give the U-values for

the various types of Ytong walls. In each

case, these values are so low that extra

insulation material becomes

superfluous and the overall insulation

level K55 is easily achieved.

This is because the insulation values of

the various building materials are now

laid down in an addendum to stan-

dard NBN B 62-002 and they allow an

inspector to firmly establish the overall

insulation level of your dwelling.

Is it still possible to build without additional insulation material?

You can simply use Ytong to build a wall

of traditional thickness (inner leaf +

cavity + facing brick or massive wall +

stucco = 30 cm)

without having to install an additional

layer of insulation. A double wall

consisting of Ytong blocks of minimum

17.5 cm with facing brick and an air

cavity, as well as a massive wall

consisting of Ytong blocks of minimum

20 cm combined with plaster, remain

below the standard (U 0,6 W/m2 K).

The slightest break in the continuity of the

insulation results in cold air circulating

between the inner leaf and the insulation.

Not only can this lead to a drop in the

insulation level of the wall, it can also

produce thermal bridges. These cold

bridges can have serious repercussions

for the building in question (internal

condensation, the appearance of damp

spots on the walls).

Ytong can offer an effective solution to

this problem. Ytong is insulating in itself,

and there is no need to fit additional

insulation. No more problems caused by

poorly installed insulation.

By building with Ytong, you always get a

long-lasting insulation that is also 100%

effective. Whats more, the insulation

values of Ytong blocks exceed those

of the strictest regulations, and this auto-

matically leads to additional savings on

heating costs. All without having to

pay for your insulation!

Effective insulation

Not only does the insulation of a house

have to comply with all the applicable

regulations on paper, it also has to be

correctly put in place on site. Regrettably,

it has to be concluded that this is not

always the case. To be genuinely effective,

the insulating plates must be installed in

a specific way, namely mounted perfectly

against the inner leaf and joined together.

Facing brick

Ytong WALL WITH FACING BRICKU-values (W/m2K)

Ytong WALL WITH STUCCO U-values (W/m2K)

Ui = arithmetic value of thermal conductivityin W/m.K to standard NBN B 62-002/A1

Cavity Ytong

90 30 d

Thickness Type Ytong C2/04 C3/05 C4/06

(mm) Ui=0.10 Ui=0.12 Ui=0.15

175 0,48 0,55 0,66

200 0,42 0,49 0,59

240 0,36 0,42 0,51

Stucco Ytong

12 d

Thickness Type Ytong C2/04 C3/05 C4/06

(mm) Ui=0.10 Ui=0.12 Ui=0.15

240 0,38 0,45 0,55

300 0,31 0,37 0,45

365 0,26 0,31 0,38

Wall made from concrete blocks or other material + insulation + facing brick

The insulation material is often poorly installed on site, leading to cold bridges or moisture seeping in.

Ytong solution

No insulation material in the cavity. No risk of cold bridges or water seeping in.No chance of damaging the insulation material.This system offers 100% effective insulation for the whole lifetime of the building.

9 3 20

0 6 12 18 24 0 6 12 18 24

C30

20

10

C30

20

10

Thermal insulation

Thermal inertia

During very warm periods (or periods

with large amounts of sunshine),

a well-insulated dwelling with good

thermal inertia remains pleasantly cool

during the day, but maintains just as

good a temperature at night.

As soon as the ambient temperature

rises, any building material will absorb

a certain amount of heat.

This amount of heat per m2 is known as

the thermal capacity (B). The greater

the mass of the material, the higher the

value. A concrete block has high thermal

capacity (thanks to its mass), but low

thermal inertia because it is not

insulating. To achieve good thermal

inertia, the external wall must have a

high thermal capacity (B) so that they

absorb large amounts of heat. They must

also be insulating so that the heat does

not pass through to the other side of the

wall too quickly.

The ratio A=B.thickness/ must therefore be as high as possible.

This can only be achieved if the material

used is both insulating and heavy.

A pure insulation material has a very

low mass and cannot store up the heat.

In fierce sunshine, this then gives rise

to the caravan effect, whereby it beco-

mes unbearably hot in the interior area

within a very short space of time.

Ytong has the properties of an insula-

tion material but also a considerable

mass (between 400 and 700 kg/m2). It

therefore satisfies all the conditions for

creating good thermal inertia.

Thus, it appears that the A-value of

Ytong is higher than that of other com-

mon construction materials.

If the thermal inertia is higher

(high A-value), this results in a large

phase displacement and thermal

damping.

Apart from the insulation values,

which directly impact energy use,

it is also important to consider the

level of comfort and quality of life in

the dwelling. Here too, Ytong

distinguishes itself with its

exceptional qualities.

Two major conditions for enjoying ideal

comfort during the summer months:

With a large phase displacement F

(the difference in time between the

maximum temperatures inside and

outside), the effect of the midday sun is

only felt in the evening. Therefore,

to maintain a constant temperature you

only need to use ventilation at night.

With high thermal conductivity (the

difference between the maximum

outside temperature and the maximum

inside temperature), a heat peak of

40C outside is converted to a heat

peak of 22C inside after the phase

displacement F.

The following figure shows that Ytong

performs exceptionally on both levels.

Winter

Outside

Tem

pera

ture

fluc

tuat

ions Inside

Phase displacement

Summer

Cold staysoutside

Heat stays outside

Pleasantlywarm inside

Pleasantlycool

inside

The surface temperature of the walls

Thermal comfort is a feeling of well

being that is largely created by the com-

fort temperature tc. This is the average

of the air temperature tl and the surface

temperature tp:

No cold bridges

A cold bridge is a zone where the insula-

tion of a house is weaker.

If there are not too many cold bridges,

they have little impact on annual energy

consumption. Nevertheless, they can

have disastrous consequences.

If the surface temperature of the walls

drops below a certain temperature

(14C under normal conditions),

damp and mould problems can arise

due to air condensing on the wall.

These cold bridges and the associated

condensation problems can easily be

avoided by using Ytong U-blocks,

U-lintels or normal lintels.

the comfort zone lies between tc= 19C

and tc= 21C. The diagram shows that

in a room with a surface temperature

of 15, a feeling of comfort (tc= 20C) is

only reached if the air temperature

is 25C

Xella BE nv/saKruibeeksesteenweg 24

2070 Burcht

BelgiTel: 0032/(0)3 250 47 00 Fax: 0032/(0)3 250 47 06 E-mail:ytong-be@xella.comSite: www.xella.be

Since we know that increasing the air

temperature by 5C raises energy con-

sumption by 40%, the importance of a

higher surface temperature immedia-

tely becomes clear.

Thanks to its insulating structure,

Ytong contributes to a higher surface

temperature, thereby making it possible

to save on heating costs and guarantee

optimum comfort in the dwelling

at all times.

30

25

20

15

1010 15 20 25 30

tp(C)

tl(C)

tp= surface temperaturetc= comfort temperaturetl = air temperature

comfort zone = 19C